Tidspunkt

Beskrivelse

Abstract

Antimicrobial treatment of infectious patients is increasingly complicated by frightening rates of antimicrobial resistance in infection-causing pathogens. The development of antimicrobial resistance is driven by the use and misuse of antimicrobials. Therefore, the choice of antimicrobial treatment should be appropriate to achieve the best outcome for both current and future patients. Hospitalized patients suspected of infection are often treated empirically with antimicrobials (i.e. before microbiological results on pathogen identity and antimicrobial susceptibility are available). Institutional antibiograms (ABG), which are aggregated local antimicrobial susceptibility test (AST) results, can be used as an indicator for the expected susceptibility to antimicrobials, when choosing empirical antimicrobial treatment.
The aim of this project was to generate personalised ABGs, which predict patient-specific antimicrobial susceptibility in the hospital setting. During the project, we focused on making the results of the research operational, by developing practical implementable applications. This thesis summarizes the research and methods developed to generate personalised ABGs as a series of steps taken, starting with the institutional ABG.
The first step was to generate ABGs representing patients with hospital-acquired infections and patients with community-acquired infections, respectively. Typically, AST results are available for a limited set of antimicrobials. When patient-specific AST results become available, and a treatment must be chosen, cross-resistance and cross-susceptibility for all available treatments must be considered. The next step was therefore to develop and validate a method which uses cross-susceptibility/resistance to adjust an ABG with respect to a patient’s AST results (Paper I). The next patient-specific factor considered was the association between prior antimicrobial exposure and increased resistance at the patient level (Paper II). The results indicate to which degree the susceptibilities should be adjusted, for patients previously exposed to antimicrobials. A mathematical method was developed to modify the ABG with respect to a patient’s prior antimicrobial exposure. This method also served as an operationalisation of Paper II. The method was extended to modify the ABG with respect to both patient-specific prior exposure to antimicrobials and AST results (Patent pending). Future work involves the validation of this method. During the project the developed methods were implemented in an existing software solution for antimicrobial stewardship, Treat Steward.